Soil probes have been available to prairie producers, agronomists and meteorologists for more than two decades. However those early units could not always provide the expected depth of actionable information.
For one thing, probes did not have the agronomic software to make sense of what they were reading. But that’s changing. As data collection becomes more intense and computer modelling becomes more accurate, the soil probe is becoming more useful.
While the evolution of probe technology is important, what happens on top of the probe is what makes it valuable. Data extracted from the earth in 2021 is far more useful than data extracted 20 years ago.
On the Canadian Prairies, a leading specialist in pulling useful data from a soil probe is Guy Ash, agrometeorologist with Metos Pessl Canada.
He says Pessl instruments turn field data into information an agronomist can use to make recommendations.
“The probe measures a number of different parameters, including soil moisture, salinity and temperature at every 10-centimetre depth,” says Ash. He added that retrieve time is adjusted to log data once every 15 minutes.
Ash says the short intervals for data retrieval are necessary.
“Once a day isn’t adequate because if there’s a shower or some change, you won’t see that change down in the soil. You may not need reporting that often, but when the values change, then it’s necessary.
“Pessl builds multi-function systems, not just probes. When you gather data from a number of sensors, including the probe, you have information that can help you throughout the entire growing cycle.
“For example, soil moisture is a gas gauge for crops. If you know how much soil moisture you have available for your crop, then you make better decisions on crop staging, heat units, spraying fungicides, insecticides, herbicides, when to begin harvest and a multitude of factors like that.”
Ash emphasizes that the probe is only one component in the overall Pessl field station. He says one significant benefit of the station is knowing the precise weather forecast for a specific field. This affects decisions on spray applications and harvest planning.
All the data is fed into a work planning tool that crunches, then spits out recommendations on all field operations. It’s then up to the farmer to make their decision, based on this information.
“Without a system, data is useless. Data goes into what I call a traffic light. If you’re considering a fungicide application, the work planning tool gives you a red light if it’s not feasible. Yellow light says proceed carefully. And you get green if the situation is right.
“In-crop nutrition is a major issue. Crop potential is dependent on soil moisture. If the work planning tool says you have good soil moisture, then applying nitrogen should give you a good return on investment. You might pick up seven or eight bushels of wheat just by knowing there’s enough soil moisture to justify in-crop application.
“If I have a four-foot profile and I see there’s nine inches of stored water down there, then I’ll manage that field differently than if I only have four inches of stored water.”
There’s a reluctance by some expanding farmers to consider probes in addition to their weather stations. Their concern is the daunting task of buying, installing and using enough probes to get valuable information on a 20,000 acre farm. How can the agronomist extract good recommendations from such a data mountain?
“There are many ways to do this. You can look at your soil zones across the farm and install probes in representative locations. Or, if you don’t want probes, you can run a water balance model on each field. Based on the information you already have on the soil characteristics, you can fine tune each field every time you have new information.
“Our software lets you do it both ways. Either the water-balance model or actual probes in the field. If you want to use probes, you should install them at the major soil points, which are governed by the major elevation changes across the field.
“You want a number of tools to make your decision. You want satellite imagery, soils variability, location of probes in the field and soil sampling. We have a mobile lab that allows you to do your own in-field soil chemistry and plant tissue analysis. Within three hours you can know the level of nutrients in your soil. You need the whole set of holistic tools to make optimal use of your soil. But none of that replaces boots on the ground. You still need the human element.”
Ash says that if a farmer makes this investment, he’s looking for a return on investment of three-to-one or four-to-one. Eliminating the waiting period for conventional lab results can create that favourable ROI ratio.